The proposed research includes the following projects: 1) Study of the dynamics of steroid hormones in human endometrium by tracer methods involving the perfusion of labeled estradiol, estrone, progesterone and 20 intracellular and intranuclear concentrations of the hormones will be determined. Endogenous levels of the hormones in various types of endometria, decidua and fallopian tubes will be compared with the blood levels of the steroid in the donor. Labeled progesterone will be injected into pregnant sheep and monkeys and the specific activities in blood samples from umbilical, uterine and maternal veins will be measured to determine the relative rates at which the placental hormone is released toward the maternal and fetal circulations. Measurement of the rates of 16 alpha-hydroxylation of dehydroisoandrosterone sulfate in men and evaluation of the effect of estrogens and progesterone on these rates. distribution, transit times and non-steady state of a hormone.